Nonlinear optical devices comprising a grating of periodically poled regions and based on quasi-phase matching (QPM) have been developed for doubling the frequency of an input optical signal to generate a second harmonic output signal. Some of these devices have been developed for obtaining broadband QPM waveguide converters. While being efficient in providing broadband second harmonic generation (SHG), the efficiency curves of broadband SHG suffers from ripples which are not appropriate for broadband SHG response.
Therefore, there is a need for an improved QPM wavelength converter.